<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			#head{
				width: 5px;
				height: 5px;
				border: 1px solid red;
				position: relative;
				margin: 0 auto;
			}
			#head>span{
				display: block;
				width: 0;
				height: 3px;
				background: #ec4828;
				position: absolute;
				transition: width .3s;
			}
			#head>span:nth-child(1){
				left: 0;
				bottom: 0;
			}
			#head>span:nth-child(2){
				right: 0;
				bottom: 0;
			}
			#head:hover>span{
				width: 50px;
			}
		</style>
	</head>
	<body>
		<div id="head">
			<span></span>
			<span></span>
		</div>
	</body>
</html>
